Dunkirk problem

John Mills_3

We put in a Dunkirk Extreme today. Taco pump was locked up. Effikal damper just goes round in circles, won't stop in the open position to trigger the spark. What's this world coming to?

Anyway, any experience with the damper problem? Didn't have time to troubleshoot but if someone has experienced this, what was it? Honeywell electronic aquastat, mis-wired wiring harness or something in the damper?

Larry_7

Round and round

Just thinking out loud but I believe that damper normally continues on around after call for heat is satisfied, then continues in the same direction on the next call. That is to say it makes a full revolution every other cycle? Sounds like you may be losing the call for heat between the time the damper begins to open and the time it's supposed to click the end switch. I'd try jumping out the t-stat first. Maybe high amperage in the t-stat circuit causing anticipator to falsely cycle off, but if that was the case, it would need to have time to cool down before attempting to call again. Does it retry again immediately or is there a delay between cycles?

An aquaintance of mine has been leaving the damper completely out of his new installs for some time now.... His reasoning is a small loss of AFUE is better than nightmare service calls on damper problems. He should have a pretty good pile of dampers by now. Go figure.

Interesting problem you have there but I'm at a loss for any other guesses than the one I mentioned.

Good Luck

Larry

John Mills_3

Thanks for the reply Larry. Actually was jumped out, not on a stat. LED on aquastat didn't show loss of call for heat.

John Mills_3

Damper problem fixed. Reversed polarity on the 24v going to the spark module.

Seems Dunkirk switched from Honeywell S86 to a UTEC control and that required the opposite polarity. White to ground not 24v. Schematic shows it that way but apparently some of the workers were in the habit of white to 24v and wired them backwards! If you have a Dunkirk with the damper spinning like that, reverse the black & white to the spark module.

Now just gotta change the pump.

Bill NTSG

Didja' try..

..giving the pump a little love tap? The handle of my largest screwdriver is usually sufficient. Some times a body at rest tends to remain at rest, until you get it moving. I have had a few 007's that responded to this treatment and went on to run ok.

Larry_7

Ain't solid state freaky

Real nightmare sometimes. Difficult to pinpoint the offending component. Closest you can get sometimes is that the problem is just "in there somewhere?" I hate throwing new modules at furnaces. Even when it corrects the problem I still have no idea what the heck was wrong. That was a good find and could easily have been overlooked. Thanks for the enlightenment.

Larry